TIG welding equipment and TIG welding method

ABSTRACT

TIG welding equipment includes a first articulate robot having a first arm, a TIG torch holding member for holding a TIG torch at a specified position so that the TIG torch can perform a weaving operation, and a filler wire guide moving member formed so as to surround the TM torch holding member and holdingly moving a filler wire guide in Z-axis direction.

TECHNICAL FIELD

The present invention relates to a TIG welding apparatus and a TIGwelding method for performing a TIG welding process on a surface of aworkpiece while supplying a filler wire from a filler wire guide to aspace to generate an arc therein between a TIG torch and the workpiece,thereby forming a bead on the surface of the workpiece.

BACKGROUND ART

Heretofore, there is known a TIG welding process for supplying a fillerwire to a space to generate an arc therein between a TIG torch and aworkpiece, thereby forming a bead on a surface of the workpiece.

For example, motorcycle frames include a thin workpiece and a thickworkpiece, which are made of aluminum or aluminum alloy, that overlapeach other to provide a weld region. Then, a TIG welding process isperformed on the weld region to form a scale-like bead in the weldregion, joining the two workpieces.

The TIG welding process for the two workpieces requires much more heatenergy to be consumed than a process of welding workpieces made of ironor the like.

The motorcycle frames are disposed in positions which attract publicattention. Therefore, the quality of the scale-like bead governs thecustomer attraction capability of the motorcycle frames.

For this reason, the motorcycle frames are TIG-welded by skilledtechnicians of the TIG welding process.

It is not easy to hand down the TIG welding techniques from the skilledtechnicians to general welding technicians. Further, it is difficult toincrease the production efficiency of motorcycle frames even when theskilled technicians perform the TIG welding process.

Attempts have been made to cause an articulated robot to perform the TIGwelding process which has been performed by the skilled technicians,thus increasing the frame production efficiency.

In such an articulated robot, a TIG torch and a filler wire guide areheld by an arm of the articulated robot, and a filler wire is suppliedfrom the filler wire guide to a space defined between the TIG torch anda weld region of two workpieces. The TIG torch is oscillated in aweaving action for performing a TIG welding process.

However, when the TIG torch makes a weaving action, a position of theTIG torch and a position of the filler wire with respect to the surfacesof the two workpieces vary. Therefore, the amount of the filler wirewhich is required to form the bead varies. Therefore, when the bead isformed, the state of the molten well of the filler wire that is formedin the weld region becomes unstable, forming a faulty bead. The faultybead reduces the customer attraction capability of the motorcycles.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a TIG weldingapparatus and a TIG welding method which are capable of forming afavorable scale-like bead on the surface of a workpiece using anarticulated robot.

According to the present invention, a TIG welding apparatus performs aTIG welding process on a surface of a workpiece while supplying a fillerwire from a filler wire guide to a space to generate an arc thereinbetween a TIG torch and the workpiece, thereby forming a bead on thesurface of the workpiece, the TIG welding apparatus having anarticulated robot for causing the TIG torch to make a weaving action tomove toward and away from the surface of the workpiece while causing theTIG torch to follow the surface of the workpiece, and a filler wireguide moving means held by the articulated robot, for moving the fillerwire guide toward and away from the surface of the workpiece.

The TIG welding process, which has heretofore been performed with afiller wire guide held by one hand of a skilled technician and a TIGtorch held by the other hand thereof, is carried out by the articulatedrobot which has the TIG torch and the filler wire guide. Therefore, theTIG welding process which has been performed by the skilled techniciancan be automatized to increase the production efficiency of productsthat are produced by the TIG welding process.

As the filler wire guide can be moved in a predetermined direction bythe filler wire guide moving means, the filler wire can stably besupplied to the space to generate the arc therein regardless of theweaving action that is being made by the TIG torch.

If the filler wire guide moving means has a rotating and linearly movingmechanism, then the filler wire guide can be moved in the predetermineddirection.

The rotating and linearly moving mechanism allows the filler wire guideto move opposite to the weaving action of the TIG torch, so that thefiller wire guide can have a constant apparent height with respect tothe surface of the workpiece.

The above motion of the filler wire guide does not make unstable themolten well of the filler wire on the surface of the workpiece.Therefore, a favorable bead with a high customer attraction capabilitycan easily be obtained.

According to the present invention, a TIG welding method performs a TIGwelding process on a surface of a workpiece while supplying a fillerwire from a filler wire guide to a space to generate an arc thereinbetween a TIG torch held by an arm of an articulated robot and theworkpiece, thereby forming a bead on the surface of the workpiece, theTIG welding method being characterized by causing the TIG torch to makea weaving action to move toward and away from the surface of theworkpiece while causing the TIG torch to follow the surface of theworkpiece, and moving the filler wire guide in a direction opposite tothe weaving action of the TIG torch.

By performing the TIG welding process on the workpiece while moving thefiller wire guide in a direction opposite to the weaving action of theTIG torch, the apparent height of the filler wire guide with respect tothe surface of the workpiece is made constant. In this manner, duringthe TIG welding process, the filler wire can stably be supplied to thespace to generate the arc therein. Accordingly, the molten well of thefiller wire on the surface of the workpiece is not made unstable.Therefore, a favorable bead with a high customer attraction capabilitycan easily be obtained.

The filler wire guide is held on the arm of the articulated robot by thefiller wire guide moving means, and the TIG torch is held on the arm ofthe articulated robot by the TIG torch holding means. When the fillerwire guide moving means moves in a certain direction, the filler wireguide is moved. When the articulated robot moves in a certain direction,the TIG torch makes the weaving action. When the articulated robot movesalong the surface of the workpiece, the TIG torch follows the surface ofthe workpiece.

Since the arm of the articulated robot holds the TIG torch and thefiller wire guide, causes the TIG torch to make the weaving action withrespect to the surface of the workpiece and follow the surface of theworkpiece, and also causes the filler wire guide to move in a certaindirection with respect to the surface of the workpiece, the TIG weldingprocess, which has heretofore been performed by a skilled technician isautomatized, thus increases the production efficiency of products thatare produced by the TIG welding process.

According to the present invention, a TIG welding apparatus performs aTIG welding process on a surface of a workpiece while supplying a fillerwire from a filler wire guide to a space to generate an arc thereinbetween a TIG torch and the workpiece, thereby forming a bead on thesurface of the workpiece, the TIG welding apparatus being characterizedby a TIG torch moving means held by an arm of an articulated robot, forcausing the TIG torch to make a weaving action to move toward and awayfrom the surface of the workpiece, and a filler wire guide holding meansfor holding the filler wire guide on the arm of the articulated robot.

Inasmuch as the TIG welding process, which has heretofore been performedwith a filler wire guide held by one hand of a skilled technician and aTIG torch held by the other hand thereof, is carried out by thearticulated robot which has the TIG torch and the filler wire guide, theTIG welding process which has been performed by the skilled techniciancan be automatized to increase the production efficiency of productsthat are produced by the TIG welding process.

As the filler wire guide is held by the filler wire guide holding means,the position of the filler wire with respect to the surface of theworkpiece can be held constant. Therefore, the filler wire can stably besupplied to the space to generate the arc therein. Consequently, themolten well of the filler wire on the surface of the workpiece is notmade unstable.

The TIG torch moving means causes the TIG torch to make a weaving actionin directions to move toward and away from the surface of the workpiece.The weaving action makes it possible to form a favorable scale-like beadon the surface of the workpiece, resulting in an increased customerattraction capability.

The TIG torch moving means may employ a rotating and linearly movingmechanism to cause the TIG torch to make the weaving action.

According to the present invention, a TIG welding method performs a TIGwelding process on a surface of a workpiece while supplying a fillerwire from a filler wire guide to a space to generate an arc thereinbetween a TIG torch held by an arm of an articulated robot and theworkpiece, thereby forming a bead on the surface of the workpiece, themethod being characterized by causing the TIG torch to make a weavingaction to move toward and away from the surface of the workpiece whilecausing the arm of the articulated robot to follow the surface of theworkpiece.

Since the TIG torch makes the weaving action with respect to the surfaceof the workpiece and follows the surface of the workpiece, a favorablebead with a high customer attraction capability can easily be obtained.

The filler wire guide is held on the arm of the articulated robot by thefiller wire guide holding means, and the TIG torch is held on the arm ofthe articulated robot by the TIG torch moving means. When the TIG torchmoving means moves in a certain direction, the TIG torch makes theweaving action. When the arm of the articulated robot moves along thesurface of the workpiece, the TIG torch follows the surface of theworkpiece.

Since the arm of the articulated robot holds the filler wire guide, andcauses the TIG torch to make the weaving action with respect to thesurface of the workpiece and follow the surface of the workpiece, thefiller wire is stably supplied to the space to generate the arc thereinduring the TIG welding process. Therefore, the molten well of the fillerwire on the surface of the workpiece is not made unstable.

The TIG welding process that has heretofore been performed by a skilledtechnician is automatized, thus increasing the production efficiency ofproducts that are produced by the TIG welding process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a TIG welding apparatus according to anembodiment of the present invention;

FIG. 2 is a front elevational view of the TIG welding apparatusaccording to the embodiment;

FIG. 3 is a perspective view of a workpiece on which a TIG weldingprocess is performed;

FIG. 4 is a cross-sectional view taken along line IV-IV across theworkpiece shown in FIG. 3;

FIG. 5 is a view showing a TIG welding process on a surface of theworkpiece shown in FIG. 3;

FIG. 6 is a diagram showing a weaving action of a TIG torch upon theelapse of time; and

FIG. 7 is a perspective view of a modification of the TIG weldingapparatus according to the embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, a TIG welding apparatus 10 according to anembodiment of the present invention has a first articulated robot 14having a first arm 12 and being operable to move the first arm 12 in anydesired direction; a TIG torch holding means 18 mounted on the first arm12 for holding a TIG torch 16 in a desired position; and a filler wireguide moving means 22 mounted on the first arm 12 in surroundingrelation to a portion of the TIG torch holding means 18, for holding afiller wire guide 20 and moving the filler wire guide 20 in a direction(Z-axis direction) toward and away from a workpiece.

As shown in FIG. 2, a controller 24 transmits a first control signal S1to the first articulated robot 14 to move the first arm 12 in anydesired direction. The first articulated robot 14 has six axes J1-J6.The first control signal S1 includes control signals S11-S16 for therespective axes J1-J6.

The TIG torch 16 has a tungsten electrode 26 on its distal end. Thetungsten electrode 26 is supplied with an alternating current up toseveral hundreds ampere from a TIG welding machine 30 through a firstcable 28. The alternating current is applied to the tungsten electrode26 when the controller 24 transmits a second control signal S2 to theTIG welding machine 30. When the alternating current is applied to thetungsten electrode 26, the TIG torch 16 starts a TIG welding process.

As shown in FIG. 1, the TIG torch holding means 18 has a fixed frame 32held by the first arm 12 of the first articulated robot 14, and a guiderail 34 fixedly mounted in the fixed frame 32 and extending in theZ-axis direction.

The TIG torch holding means 18 also has a first holder 36 fixed to thefixed frame 32 and holding the TIG torch 16, a second holder 40 fixed toan upper portion of the fixed frame 32 and holding a servomotor 38, anda cam 44 mounted on a rotational shaft 42 of the servomotor 38.

The cam 44 should preferably be a plate cam having a tip end. A rod 46is secured to the tip end of the cam 44 and projects from a planarsurface of the cam 44.

The filler wire guide moving means 22 comprises a movable frame 48 and aslide member 50 fixedly mounted in the movable frame 48 for movementalong the guide rail 34.

A restraint member 54 having a horizontally elongate slot 52 definedtherein projects from an upper portion of the movable frame 48. The rod46 projecting from the cam 44 is inserted in the slot 52.

The filler wire guide moving means 22 is thus held by the TIG torchholding means 18 via the slide member 50 and the restraint member 54.

As shown in FIG. 2, the filler wire guide 20 is connected to a fillerwire supply device 58 via a filler wire guide tube 56. When thecontroller 24 transmits a fourth control signal S4 to the filler wiresupply device 58, the filler wire supply device 58 supplies a fillerwire 62 wound around a filler wire reel 60 through the filler wire guidetube 56 to the filler wire guide 20. As shown in FIG. 1, the filler wireguide 20 is held by a joint member 64 that is fixed to a lower portionof the movable frame 48.

Motion of the filler wire guide 20 at the time the controller 24supplies a third control signal S3 to the servomotor 38 will bedescribed below with reference to FIGS. 1 and 2.

When the third control signal S3 is transmitted to the servomotor 38,the rotational shaft 42 of the servomotor 38 turns in oscillation withinthe range of an angle θ, as shown in FIG. 1. Based on this movement, thetip end of the cam 44 reciprocates in the Z-axis directions within therange of the angle θ.

At this time, the rod 46 is restrained by the slot 52 in the restraintmember 54. Therefore, the reciprocating movement of the cam 44 in theZ-axis directions is transmitted to the restraint member 54 via the rod46, causing the slide member 50 to move in the Z-axis directions alongthe guide rail 34. The reciprocating movement of the cam 44 in theZ-axis directions also causes the movable frame 48 to move in the Z-axisdirections. Therefore, the filler wire guide 20 is movable in the Z-axisdirections based on the third control signal S3.

When a workpiece 66 is positioned closely to the TIG torch 16 of the TIGwelding apparatus 10 according to the present embodiment, as shown inFIG. 2, the workpiece 66 can be TIG-welded.

The workpiece 66 is gripped by a frame holder 72 mounted on a second arm70 of a second articulated robot 68. The controller 24 transmits a fifthcontrol signal S5 to the second articulated robot 68 so that the secondarm 70 operates to move and position the workpiece 66 relatively closelyto the TIG torch 16. The TIG welding machine 30 and the frame holder 72are connected to each other via a second cable 74 serving as a groundline.

Using the TIG welding apparatus 10 according to the present embodiment,the workpiece 66, which may be constructed as shown in FIG. 3, can beTIG-welded into an aluminum frame for a motorcycle body.

The workpiece 66 comprises first and second castings 76, 78 and a mainpipe 80.

For producing the aluminum frame, a portion of the first casting 76 anda portion of the main pipe 80 are superposed one on the other, forming aweld region 82 as shown in FIG. 4. A portion of the second casting 78and a portion of the main pipe 80 are superposed one on the other,forming another weld region that is different from the weld region 82.

Then, the workpiece 66 is gripped by the frame holder 72. As shown inFIG. 5, the weld region 82 is positioned so as to lie along a desireddirection, i.e., the X-axis direction (see FIG. 1), closely to thetungsten electrode 26 of the TIG torch 16.

Then, an alternating current is applied to the tungsten electrode 26 togenerate an arc discharge in a space 84 defined between the weld region82 and the tungsten electrode 26. The filler wire 62 is supplied fromthe filler wire guide 20 into the space 84.

At this time, as shown in FIG. 1, since the cam 44 reciprocates in theZ-axis directions based on the oscillation of the rotational shaft 42,the filler wire guide moving means 22 can move the filler wire guide 20in the Z-axis directions.

The first articulated robot 14 is supplied with the first control signalS1 from the controller 24. When the control signal S15 of the firstcontrol signal S1 is transmitted to the axis J5, the first arm 12 of thefirst articulated robot 14 oscillates in the Z-axis directions. Sincethe oscillation of the first arm 12 is transmitted to the TIG torchholding means 18, the TIG torch 16 makes a weaving action to oscillatetoward and away from the weld region 82 of the workpiece 66.

The weaving action of the TIG torch 16 is controlled to move opposite tothe oscillation of the filler wire guide 20. This weaving action of theTIG torch 16 allows the filler wire guide 20 to have an apparent heightthat is constantly kept as a predetermined height with respect to theweld region 82 of the workpiece 66. Therefore, the filler wire 62 canstably be supplied to the space 84.

The weaving action of the TIG torch 16 and the stable supply of thefiller wire 62 from the filler wire guide 20 to the space 84 make itpossible to form a favorable scale-like bead 86 in the weld region 82.

When the TIG torch 16 makes a weaving action while the first arm 12 ofthe first articulated robot 14 is moving in the X-axis direction, aplurality of scale-like beads 86 are formed in partly overlappingrelation along a straight path.

The aluminum frame with the scale-like beads 86 thus formed for use on amotorcycle will attract public attention because it will be positionedon a side of the rider's seat of the motorcycle. Therefore, if thealuminum frame with the scale-like beads 86 formed by the TIG weldingapparatus 10 according to the present embodiment is used as an aluminumframe for a motorcycle, then it increases the customer attractioncapability of the motorcycle.

The relationship between the weaving action of the TIG torch 16 in theTIG welding process performed by the TIG welding apparatus 10 accordingto the present embodiment, the alternating current applied to thetungsten electrode 26, and the amount of the filler wire 62 that issupplied will be described from the standpoint of the elapse of time.

As shown in FIG. 6, the TIG torch 16 makes a weaving action cyclicallyin periods of N. Specifically, the height of the TIG torch 16, which isinitially H1, changes to H2 after 0.9N (H1>N2). That is, the tip end ofthe tungsten electrode 26 approaches the weld region 82 up to the heightH2. Thereafter, the height of the TIG torch 16 changes from H2 to H1within 0.1N.

The temperature of the space 84 in which the arc is generated increasesas the TIG welding time t elapses. If a certain alternating current iscontinuously applied to the tungsten electrode 26, the workpiece 66 hasits temperature increased, resulting in an increase in the amount of thefiller wire 62 to be melted into the weld region 82.

The alternating current applied to the tungsten electrode 26 is reducedstepwise to change the amount of generated heat for stabilizing thebeads.

Since the TIG welding apparatus 10 according to the present embodimentautomatizes the TIG welding process that has been performed by theskilled worker, the production efficiency of products that are producedby the TIG welding process is greatly increased.

A modification of the TIG welding apparatus 10 according to the presentembodiment will be described below.

The modification is of approximately the same structure as the TIGwelding apparatus 10 shown in FIGS. 1-6, but differs therefrom asfollows:

As shown in FIG. 7, a filler wire guide holding means 100 has a fixedframe 102 held by the first arm 12 of the first articulated robot 14,and a guide rail 104 fixedly mounted in the fixed frame 102 andextending in the Z-axis direction.

A TIG torch moving means 106 has a slide table 108 movable along theguide rail 104, a first holder 110 fixed to the slide table 108 andholding the TIG torch 16, a second holder 112 fixed to an upper portionof the slide table 108 and holding the servomotor 38, and the cam 44mounted on the rotational shaft 42 of the servomotor 38.

The restraint member 54 having the horizontally elongate slot 52 definedtherein projects from the upper portion of the fixed frame 102. The rod46 is inserted in the slot 52.

The filler wire guide 20 is held by the joint member 64 that is fixed toa lower portion of the fixed frame 102.

According to the modification of the TIG welding apparatus 10, when thethird control signal S3 is transmitted to the servomotor 38, therotational shaft 42 of the servomotor 38 turns in oscillation within therange of the angle θ. Based on this movement, the tip end of the cam 44reciprocates in the Z-axis directions within the range of the angle θ.

The reciprocating movement of the cam 44 in the Z-axis directions causesthe slide table 108 to reciprocate in the Z-axis directions. Therefore,the slide table 108 can move along the guide rail 104. Therefore, theTIG torch 16 is movable in the Z-axis directions based on the thirdcontrol signal S3.

As the cam 44 reciprocates in the Z-axis directions based on theoscillatory motion of the rotational shaft 42, the TIG torch movingmeans 106 can move the TIG torch 16 in the Z-axis directions. The TIGtorch 16 makes a weaving action to oscillate toward and away from theweld region 82 of the workpiece 66.

Inasmuch as the filler wire guide 20 is held by the joint member 64, thefiller wire guide 20 is constantly held in a predetermined position withrespect to the weld region 82 of the workpiece 66 regardless of theweaving action of the TIG torch 16. Therefore, the filler wire 62 canstably be supplied to the space 84.

The TIG welding apparatus and the TIG welding method according to thepresent invention are not limited to the above embodiments, but may takevarious arrangements without departing from the scope of the presentinvention.

INDUSTRIAL APPLICABILITY

According to the present invention, as described above, since the TMtorch is caused to make a weaving action and the filler wire guide iscaused to move opposite to the TIG torch, the apparent height of thefiller wire guide with respect to the surface of the workpiece is keptas a constant height. Therefore, the filler wire can stably be suppliedto the arc generating space between the TIG torch and the surface of theworkpiece, easily forming a favorable scale like bead with a highcustomer attraction capability on the surface of the workpiece.

According to the present invention, furthermore, the TIG torch is causedto make a weaving action and the filler wire guide is held at a constantposition with respect to the surface of the workpiece. Consequently, thefiller wire can stably be supplied to the arc generating space betweenthe TIG torch and the surface of the workpiece, easily forming afavorable scale-like bead with a high customer attraction capability onthe surface of the workpiece.

1. A TIG welding apparatus for a TIG welding process on a surface of aworkpiece while supplying a filler wire from a filler wire guide to aspace to generate an arc therein between a TIG torch and said workpiece,thereby forming a bead on said surface of said workpiece, said TIGwelding apparatus comprising: an articulated robot for impartingmovement to said TIG torch to make a weaving action to move toward andaway from said surface of said workpiece; and filler wire guide movingmeans held by said articulated robot, said filler wire guide movingmeans being independently movable for moving said filler wire guiderelative to the movement of said TIG torch in directions toward and awayfrom said surface of said workpiece, wherein said filler wire guidemoves in a direction opposite to said weaving action of said TIG torchand said filler wire guide is moved a predetermined distance toward andaway from said surface of said workpiece while maintaining a relativelyconstant predetermined apparent height with respect to a weld region ofthe workpiece.
 2. A TIG welding apparatus according to claim 1, whereinsaid filler wire guide moving means has a rotating and linearly movingmechanism.
 3. A TIG welding method for a TIG welding process on asurface of a workpiece while supplying a filler wire from a filler wireguide to a space to generate an arc therein between a TIG torch held byan aim of an articulated robot and said workpiece, thereby forming abead on said surface of said workpiece, comprising: moving said TIGtorch to make a weaving action to move toward and away from said surfaceof said workpiece for making said filler wire guide movable with respectto said TIG torch in directions toward and away from said surface ofsaid workpiece; and independently moving said filler wire guide withrespect to said TIG torch in a direction opposite to a direction of saidweaving action of said TIG torch and said filler wire guide is moved apredetermined distance toward and away from said surface of saidworkpiece while maintaining a relatively constant predetermined apparentheight with respect to a weld region of the workpiece.
 4. A TIG weldingapparatus for a TIG welding process on a surface of a workpiece whilesupplying a filler wire from a filler wire guide to a space to generatean arc therein between a TIG torch and said workpiece, thereby forming abead on said surface of said workpiece, said TIG welding apparatuscomprising: an articulated robot for imparting movement to an arm ofsaid articulated robot to follow said surface of said workpiece; TIGtorch moving means held by said arm of said articulated robot, forimparting movement to said TIG torch to make a weaving action to movewith respect to said arm in directions toward and away from said surfaceof said workpiece; and filler wire guide holding means for independentlyholding said filler wire guide fixed on said arm of said articulatedrobot, said filler wire guide holding means being independently movablefor moving said filler wire guide relative to the movement of said TIGtorch.
 5. A TIG welding apparatus according to claim 4, wherein said TIGtorch moving means has a rotating and linearly moving mechanism.
 6. ATIG welding method for a TIG welding process on a surface of a workpiecewhile supplying a filler wire from a filler wire guide to a space togenerate an arc therein between a TIG torch held by an arm of anarticulated robot and said workpiece, thereby forming a bead on saidsurface of said workpiece, comprising: imparting movement to said TIGtorch to make a weaving action to move with respect to said arm indirections toward and away from said surface of said workpiece with saidfiller wire guide being independently fixed on said arm of saidarticulated robot, while causing said arm of said articulated robot tofollow said surface of said workpiece; and imparting independentmovement to said filler wire guide holding means for moving said fillerwile guide relative to the movement of said TIG torch.
 7. A TIG weldingapparatus for a TIG welding process on a surface of a workpiece whilesupplying a filler wire from a filler wire guide to a space to generatean arc therein between a TIG torch and said workpiece, thereby forming abead on said surface of said workpiece, said TIG welding apparatuscomprising: an articulated robot for imparting movement to said TIGtorch to make a weaving action to move toward and away from said surfaceof said workpiece a predetermined distance while causing said TIG torchto follow said surface of said workpiece; and filler wire guide movingmeans held by said articulated robot, said filler wire guide movingmeans moving said filler wire guide a predetermined distance toward andaway from said surface of said workpiece while maintaining a relativelyconstant predetermined apparent height with respect to a weld region ofthe workpiece.
 8. A TIG welding apparatus according to claim 7, whereinsaid filler wire guide moving means has a rotating and linearly movingmechanism.
 9. A TIG welding apparatus according to claim 7, wherein saidfiller wire guide moves opposite to said weaving action of said TIGtorch while maintaining the relatively constant predetermined apparentheight with respect to the weld region of the workpiece.
 10. A TIGwelding method for a TIG welding process on a surface of a workpiecewhile supplying a filler wire from a filler wire guide to a space togenerate an arc therein between a TIG torch held by an arm of anarticulated robot and said workpiece, thereby forming a bead on saidsurface of said workpiece, comprising: moving said TIG torch to make aweaving action to move toward and away from said surface of saidworkpiece a predetermined distance while causing said TIG torch tofollow said surface of said workpiece; and moving said filler wire guidea predetermined distance in a direction opposite to a direction of saidweaving action of said TIG torch while maintaining a relatively constantpredetermined apparent height with respect to a weld region of theworkpiece.